Along with development of technology, microelectromechanical oscillators are used to gradually replace existing oscillators. Generally, the microelectromechanical oscillators are used for a low-frequency application and a high-frequency application. In the low-frequency application, the microelectromechanical oscillator is used to replace a conventional quartz oscillator, and in the high-frequency application, the microelectromechanical oscillator is used to replace a surface acoustic wave (SAW) filter and a film bulk acoustic resonator (FBAR).
However, regarding a present microelectromechanical oscillator, besides a Q-factor (a Q value) of the device, impedance is also an important indicator that influences an output thereof. For example, in case of the low-frequency application, if the impedance of the device is excessively high, it represents that a gain of an amplifier is required to be increased, which may increase a current of the amplifier to cause relatively high power consumption. Moreover, in case of the high-frequency application of the communication system, the higher the impedance of the device is, the closer a reflection coefficient of the device approaches to 1, i.e. the device is not suitable to be used in the communication system because of its high insertion loss. Therefore, how to resolve the problems of the present microelectromechanical oscillator is an important issue to be developed.